Sudoku Puzzle © Kevin Stone

R2C1 is the only square in row 2 that can be <6>

R7C1 can only be <8>

R7C5 can only be <4>

R7C7 can only be <2>

R7C9 can only be <7>

R7C3 can only be <6>

R2C5 is the only square in row 2 that can be <7>

R2C9 is the only square in row 2 that can be <2>

R4C6 is the only square in row 4 that can be <1>

R4C4 is the only square in row 4 that can be <7>

R4C9 is the only square in row 4 that can be <4>

R5C4 is the only square in row 5 that can be <6>

R6C4 is the only square in row 6 that can be <4>

R9C6 is the only square in row 9 that can be <5>

R6C1 is the only square in column 1 that can be <9>

R6C6 can only be <8>

R1C4 is the only square in row 1 that can be <8>

R9C4 can only be <9>

R8C5 can only be <8>

R9C8 is the only square in row 9 that can be <8>

Squares R4C5 and R6C5 in column 5 form a simple locked pair. These 2 squares both contain the 2 possibilities <35>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.

R5C5 - removing <35> from <2359> leaving <29>

Squares R2C8 and R5C8 in column 8 form a simple locked pair. These 2 squares both contain the 2 possibilities <13>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.

R1C8 - removing <3> from <349> leaving <49>

R8C8 - removing <3> from <349> leaving <49>

Squares R1C2 and R1C7 in row 1 and R5C2 and R5C7 in row 5 form a Simple X-Wing pattern on possibility <5>. All other instances of this possibility in columns 2 and 7 can be removed.

R3C7 - removing <5> from <145> leaving <14>

Squares R4C1 and R8C1 in column 1, R4C5 and R6C5 in column 5 and R6C9 and R8C9 in column 9 form a Swordfish pattern on possibility <3>. All other instances of this possibility in rows 4, 6 and 8 can be removed.

R8C2 - removing <3> from <134> leaving <14>

Squares R3C1 (XY), R2C2 (XZ) and R4C1 (YZ) form an XY-Wing pattern on <3>. All squares that are buddies of both the XZ and YZ squares cannot be <3>.

R5C2 - removing <3> from <357> leaving <57>

Squares R3C7 (XY), R2C8 (XZ) and R9C7 (YZ) form an XY-Wing pattern on <3>. All squares that are buddies of both the XZ and YZ squares cannot be <3>.

R1C7 - removing <3> from <345> leaving <45>

R2C8 is the only square in block 3 that can be <3>

R2C2 can only be <1>

R5C8 can only be <1>

R8C2 can only be <4>

R3C1 can only be <5>

R3C9 can only be <9>

R4C1 can only be <3>

R3C5 can only be <2>

R8C9 can only be <3>

R1C8 can only be <4>

R4C5 can only be <5>

R8C1 can only be <1>

R5C3 can only be <7>

R6C5 can only be <3>

R5C2 can only be <5>

R6C9 can only be <5>

R5C7 can only be <3>

R8C8 can only be <9>

R1C2 can only be <3>

R9C3 can only be <3>

R9C7 can only be <4>

R9C2 can only be <7>

R1C7 can only be <5>

R3C7 can only be <1>

R1C3 can only be <2>

R3C3 can only be <4>

R5C5 can only be <9>

R1C6 can only be <9>

R5C6 can only be <2>